Cylinder vacuum cleaners are well known and usually comprise a main body and a wand and hose assembly which is attached to the main body. The main body comprises a motor and fan unit for generating an airflow and separating apparatus for separating dirt and dust from the airflow. Commonly, the separating apparatus takes the form of a cyclonic separator or other separating media, such as a bag. The wand and hose assembly comprises a length of flexible hose which is attached to the main body of the vacuum cleaner at one end. A rigid wand is attached to the other end of the hose. The airflow enters the main body through the wand and hose assembly which is manipulated by a user to clean a floor surface.
A wand typically includes two hollow tubes which are telescopically connected to one another. An example of this type of wand is shown in U.S. Pat. No. 3,083,041. A first tube is rigidly connected to a handle and a second tube slides telescopically within the first tube. It is common to provide a form of releasable locking device to secure the two tubes in a fixed relationship with respect to one another so that the wand can be used to clean a surface. It is also common to provide a plurality of lockable positions so that the overall length of the wand can be adjusted to suit a particular user. Usually, the two tubes can be retracted inside one another for storage. This reduces the overall length of the wand for storage.
Whilst the above type of wand is simple to operate and to manufacture, a two tube arrangement cannot be reduced to a size below a half of its maximum extension. Therefore, such a wand is bulky and difficult to store. This type of wand also creates packaging problems for the manufacturer because the box in which the product is supplied has to be of a sufficient size to accommodate the bulky wand.
An alternative arrangement is shown in EP 1 380 247. In this arrangement, a wand assembly having four tubes is shown. The tubes are able to slide telescopically with respect to one another. The outermost tube carries a handle and acts as a storage tube into which the remaining three tubes slide telescopically. By providing four tubes, the wand assembly can have the same extended length as a two tube arrangement, but each tube can be correspondingly shorter than if only two tubes were provided. Therefore, when the tubes are telescopically retracted into one another, the overall length of the wand assembly is significantly reduced when compared to a two tube arrangement. This has benefits for storage and shipping purposes.
When multiple tubes are provided in a wand assembly, it is important to ensure that each tube fits securely against an adjacent tube with little or no play between the tubes when they are locked in extended positions relative to one another. Even if the connections between adjacent tubes only allow a small amount of play (or “wobble”), the amount of play is multiplied by the number of connections. In a four tube wand assembly, there are three connections. Therefore if each connection allows a few degrees of play between the respective tubes in any direction, then the wand will bend noticeably in use. This bending effect may reduce the structural stability of the wand assembly and the perceived quality of the wand assembly.
In some wand assemblies, this problem is addressed by manufacturing at least some of the telescopic tubes are from a metal, such as aluminium. The use of metal tubes means that the tubes can be manufactured to high tolerances, resulting in little or no play between tubes at connection points. However, aluminium is expensive to produce, and increases the weight of a wand assembly.
Known arrangements to secure two telescopically slideable tubes with respect to one another are shown in U.S. Pat. No. 3,083,041 and EP 1 106 133. In these arrangements, a wedge portion located on one of the tubes engages with a cooperating wedge portion on another tube. The interaction between the two wedges takes up any difference in the radial sizes of the tubes, securely holding the tubes with respect to one another. However, the arrangements shown in these documents are designed for use with a two tube system. This means that the central connector between the tubes can be large. A wand assembly having more than two tubes requires a smaller connector connecting each of the tubes; otherwise the tubes will not be able to slide inside one another in order to be stored.
It is desirable to have a compact and structurally sound wand assembly, in which the tubes forming part of the wand are held firmly with respect to one another even when the sizes of the tubes vary slightly as a result of the manufacturing process or other factors.